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L Rasmussen

Publications and source records attributed to L Rasmussen.

At least 73 records · Page 4Linked to original sources
PubMed1993

Signalling in cell growth and death: adequate nutrition alone may not be sufficient for ciliates. A minireview.

The initial inoculum level of Tetrahymena in a chemically defined medium determines whether the cells are capable of exponential growth. Below 750 cells ml-1, the cells fail to go into exponential growth and will die within about 20 hours. By adding certain growth stimulants, death can be postponed and the cells begin to grow after a delay which depends on the intensity of the signal. The implication is that autocrine growth factor expression might be required for cells to grow, and that these stimulants either assist its production or lower the cell threshold to its action. The findings in Tetrahymena are reviewed, and the advantages of having a cell system in which all the components of the medium can be carefully controlled is recognised.

Animals↗
PubMed1993

Three pools of lysosomal enzymes in Tetrahymena thermophila.

Secretion of lysosomal enzymes into the extracellular surroundings has been observed in many eukaryotic cells. We studied the activity of lysosomal enzymes in different subcellular fractions of Tetrahymena thermophila to get more insight into this general phenomenon. By density gradient centrifugation a light and a dense fraction of lysosomal particles were found. Electron microscopy revealed that the light fraction mainly consists of cell surface membranes. By immunostaining a lysosomal enzyme (beta-hexosaminidase) was detected on the plasma membrane. The Triton X-114 assay showed that the light fraction as well as purified cilia (an enriched source of plasma membrane) contain lysosomal enzymes predominantly covalently bound to the membrane. The dense fraction contains both membrane-bound and soluble forms of lysosomal enzymes. By labeling phagosomes/phagolysosomes with magnetic particles the dense fraction can be subdivided into two lysosomal vesicle populations: phagolysosomes and a further population of lysosomal vesicles which can not be labeled. The relationship between membrane-bound and soluble enzyme forms in phagolysosomes and this unlabeled vesicle population is different: In phagolysosomes 80% of the acid phosphatase and 20% of the beta-hexosaminidase are membrane-bound, whereas in the unlabeled vesicles 42% of the acid phosphatase and 8% of the beta-hexosaminidase are bound to the membrane. Furthermore, we present results suggesting that the unlabeled vesicle population of the dense fraction is the source of secreted lysosomal enzymes. A working model summarizing our present knowledge about the connection of the three pools of lysosomal enzymes in Tetrahymena is presented.

Acid Phosphatase↗
PubMed1992

A double-blind placebo-controlled trial of omeprazole on urinary pH in healthy subjects.

Urinary pH is related to urinary calculus formation as well as urinary infection. Omeprazole is an effective inhibitor of gastric acid secretion through inhibition of the parietal cell H+K+ATPase. In this study we have evaluated a possible effect of omeprazole on urine acidification. Ten healthy male subjects took placebo and omeprazole, 40 mg o.m., for 10 days in a double-blind placebo-controlled trial. Morning fasting urinary pH was measured on day 10 of each treatment course using a pH meter. No effect of omeprazole on urinary pH could be demonstrated. It is thus unlikely that it is necessary to take omeprazole treatment into consideration in stone screening. As omeprazole did not affect urinary pH, no urological side effects related to changes in urinary pH can be expected.

Adult↗
PubMed1992

Differential increase in activity of acid phosphatase induced by phosphate starvation in Tetrahymena.

We have studied the effects of phosphate starvation on the levels and distributions of activities of acid phosphatase and beta-hexosaminidase in cultures of Tetrahymena thermophila. The cells were grown in synthetic nutrient medium and refed every day with fresh medium. After 4 days of growth in the complete medium, the cultures were divided into two portions. One received complete medium and the other phosphate-free, but otherwise complete, medium. Population densities and activities of acid phosphatase and beta-hexosaminidase in cells plus medium and in cell-free samples were determined in aliquots removed every day before medium replacement. In cultures having complete medium the enzyme levels remained fairly constant; in the phosphate-starved cultures both total and extracellular activities of acid phosphatase increased sixfold. beta-Hexosaminidase levels remained essentially unaltered in both cases. These results indicate that phosphate starvation can induce differential increase in acid phosphatase activity in cultures of Tetrahymena. Somewhat less than 50% of the total activities of both enzymes are found in the cell-free extracellular fluid at any time.

Acid Phosphatase↗
PubMed1992

Expression of bovine immunodeficiency-like virus envelope glycoproteins by a recombinant baculovirus in insect cells.

The bovine immunodeficiency-like virus (BIV) env open reading frame (ORF) contains both sequences encoding env and sequences for exon 1 of the putative rev gene. Recombinant baculoviruses incorporating BIV env ORF sequences were constructed to characterize the expression, processing, and immunogenicity of products of the BIV env ORF in insect cells and to develop reagents to study native BIV Env glycoproteins. A recombinant baculovirus containing the entire env ORF synthesized a nonglycosylated, 20-kDa, BIV-specific protein, apparently unrelated to native BIV Env proteins. In contrast, a recombinant baculovirus containing a truncated env ORF in which the coding sequences for rev exon 1 were deleted synthesized three size classes of glycosylated proteins in insect cells related to the BIV Env precursor (gp145), surface (gp100), and transmembrane (gp45) glycoproteins observed in BIV-infected mammalian cells. Oligomers of recombinant BIV Env proteins also formed in these baculovirus-infected insect cells. Immunofluorescence staining of intact insect cells infected by the baculovirus expressing BIV Env with BIV-specific serum demonstrated that the recombinant Env glycoproteins were expressed on the cell surface. Antisera raised to recombinant Env glycoproteins immunoprecipitated native gp145, gp100, and gp45 in BIV-infected bovine cells similar to sera from animals naturally or experimentally infected with BIV.

Animals↗
PubMed1992

Immunological characterization of the gag gene products of bovine immunodeficiency virus.

The bovine immunodeficiency virus (BIV) gag gene encodes a 53-kDa precursor (Pr53gag) that is involved in virus particle assembly and is further processed into the putative matrix (MA), capsid (CA), and nucleocapsid (NC) functional domains in the mature virus. Gag determinants are also found in the Gag-Pol polyprotein precursor. To immunologically identify the major precursors and processed products of the BIV gag gene, monospecific rabbit sera to recombinant BIV MA protein and Pr53gag and peptides predicted to correspond to the CA and NC proteins and the MA-CA cleavage site were developed and used in immunoprecipitations and immunoblots of BIV antigens. Monospecific antisera to native and recombinant human immunodeficiency virus type 1 proteins were also used to identify analogous BIV Gag proteins and to determine whether cross-reactive epitopes were present in the BIV Gag precursors or processed products. The BIV MA, CA, and NC Gag proteins were identified as p16, p26, and p13, respectively. In addition to BIV Pr53gag, the major Gag precursor, two other Gag-related precursors of 170 and 49 kDa were identified that have been designated pPr170gag-pol and Pr49gag, respectively; pPr170gag-pol is the Gag-Pol polyprotein precursor, and Pr49gag is the transframe Gag precursor present in pPr170gag-pol. Several alternative Gag cleavage products were also observed, including p23, which contains CA and NC determinants, and p10, which contains a peptide sequence conserved in the CA proteins of most lentiviruses. The monospecific antisera to human immunodeficiency virus type 1 CA (p24) and NC (p7) proteins showed cross-reactivity to and aided in the identification of analogous BIV proteins. Based on the present data, a scheme for the processing of BIV Gag precursors is proposed.

Amino Acid Sequence↗
PubMed1992

The influence of induced hyperglycaemia on the characteristics of intestinal motility and bile kinetics in healthy men.

Simultaneous recording of duodenal motility and biliary scintigraphy by continuous infusion of 99mTc-dimethyl-iminodiacetic acid was performed in 16 healthy fasted men, of whom eight had an intravenous glucose bolus injection immediately after the passage of a duodenal phase III of the migrating motor complex (MMC). This was followed by a continuous intravenous infusion of glucose. Characteristics of the time-activity curves from the gallbladder area and intestinal area were related to phase activity of the duodenal MMC. The median duration of the entire MMC cycle was significantly shorter in the glucose group than in the group without glucose. The difference was caused by shortening of phase II. Spontaneous gallbladder emptying appeared in all eight subjects from the group without glucose but in only a single subject from the glucose group. The relative amount of liver bile diverted to the gallbladder in the entire cycle was significantly higher in the subjects who received glucose, and in four subjects all the hepatic bile was diverted to the gallbladder. The results demonstrate that induced hyperglycaemia exerts a pronounced effect on gastrointestinal motility and bile kinetics. Available evidence suggests that the effects are caused by a 'medical vagotomy'.

Adult↗
PubMed1992

Postprandial gallbladder emptying is related to intestinal motility at the time of meal ingestion.

The characteristics of meal-induced gallbladder emptying in healthy individuals are subject to wide variation. We hypothesized that some of the observed variation might relate to ingestion of the meal during different phases of the migrating motor complex (MMC). Recording of gastrointestinal pressure was combined with scintigraphic recording of bile kinetics during infusion of 99mTc-HIDA. The material consisted of 12 healthy men. Group 1 (n = 6) had a fat-rich meal in phase I, and group 2 (n = 6) had the meal in a phase II. With the end of the meal ingestion as zero, the following results emerged. The subjects in group 1 had a median (range) lag period before beginning of gallbladder emptying of 13.5 (9.0-22.5) min. In group 2 gallbladder emptying began during the meal ingestion in four subjects, and the median lag period was 0 min (minimum, -9.0; maximum, 13.5 (p = 0.02)). The median percentage change of gallbladder counts during the observation period of 54 min in group 1 was 11.5% (from 19% filling to 25% emptying). The corresponding figures in group 2 were 41% (from 2% to 91% emptying (p less than 0.05)). This difference was due to the difference in duration of lag periods, as the emptying rates measured from the end of the lag periods were equal. In conclusion, the onset of postprandial gallbladder emptying relates to the phase activity of the MMC at the time of ingestion.

Adult↗
PubMed1992

The effects of omeprazole on interdigestive motility and early postprandial levels of gastrin and secretin.

Ten healthy men participated in a crossover study, and the experiments took place after 10 days of treatment (40 mg omeprazole every morning). Blood samples were drawn at fixed intervals during a complete migrating motor complex (MMC) cycle. The manometric pressure tube was removed after passage of the second duodenal phase III, and an omelet (1400 KJ) tagged with 99mTc was ingested, followed by 150 ml of water tagged with 111In-diethylenetriaminepentaacetic acid. Mean plasma gastrin (pmol/l) in phases I, II, and III in the omeprazole group was 18.8, 23.3, 19.9, respectively. The corresponding figures for the placebo group were 9.3, 9.6, 9.5, respectively. All mean values for the omeprazole group were significantly higher (p less than 0.01). Mean plasma gastrin in the omeprazole group was significantly higher in phase II than in phase I (p less than 0.05). Mean plasma secretin (pmol/l) in phases I, II, and III in the omeprazole group was 1.6, 1.4, 1.1, respectively. The corresponding figures for the placebo group were 2.0, 1.7, 2.2, respectively. Mean plasma secretin in the omeprazole group was significantly lower in phases I and III (p less than 0.05). The mean incremental integrated postprandial gastrin response (pmol.30 min/l) was significantly higher in the omeprazole group (475.0 versus 97.5) (p less than 0.05). The immediate postprandial mean value of secretin was significantly lower in the omeprazole group (p less than 0.05). We conclude that 40 mg omeprazole elicits i) a phase-related increase in fasting plasma gastrin, ii) a decrease in secretin in phases I and III, iii) an augmented meal-stimulated gastrin response, and iv) a secretin response characterized by a significantly lower mean in the immediate postprandial period.

Adult↗
PubMed1992

Setting policy on environmental issues. Interview by Karen Gardner.

Perhaps more than any other type of institution, hospitals are expected to be good neighbors, which involves respect for the community and respect for the environment. Louis Rasmussen, board chairman of Carondolet Health Corp., Kansas City, MO (the parent company for Saint Joseph Health Center, a 300-bed acute care hospital in Kansas City), and a retired executive of Kansas City Power and Light Co., sees the board's role in setting responsible environmental policy for the hospital as pivotal. In 1991, Rasmussen served on the American Hospital Association's Ad Hoc Committee on Recycling. Currently, he is a member of the AHA's Congress of Hospital Trustees. Participation in these activities, as well as his professional background in both engineering and law, gives him a broad view of both environmental issues and governance. Recently, Rasmussen spoke with Trustee editor Karen Gardner about the environmental issues confronting hospitals today and the board's role in dealing with those issues.

Chlorofluorocarbons, Methane↗
PubMed1991

Chromium, lead and cadmium in Danish milk products and cheese determined by Zeeman graphite furnace atomic absorption spectrometry after direct injection or pressurized ashing.

A method for the direct determination of chromium in homogeneous samples of milk and milk products is described. Minimum sample handling and prevention of contamination was given priority. After injection of the sample into the graphite furnace, the sample was ashed in a stream of oxygen at 650 degrees C and then further ashed at 1,100 degrees C with argon as the purge gas. Zeeman background correction was used in the atomisation step at 2,300 degrees C. The detection limit was 0.7 ng/g. Direct detection of chromium in milk, using only argon as purge gas, was inferior. Non-homogeneous and solid samples, e.g. yoghurt with fruit jam and cheese, were ashed under pressure with nitric acid before analysis. The same analytical principle as used for chromium was also used for the analysis of lead and cadmium in the samples. Analytical quality control was performed for both methods and the results are reported. The results for lead, cadmium and chromium in Danish milk and milk products were in the parts per billion or parts per trillion range and compare well with literature data. The intake of lead, cadmium and chromium from milk and milk products is less than 4% of the total Danish dietary intake of these elements. It is concluded that the contribution from milk and milk products to the total intake of lead and cadmium is toxicologically insignificant and that milk and milk products are only a minor source of the essential element chromium.

Animals↗
PubMed1991

A time-dependent study of passive esophageal wall properties and collagen content in rabbits with esophageal varices.

The passive biomechanical wall properties of the esophagus were studied in rabbits with esophageal varices and controls using a four-electrode impedance technique. Stepwise pressure inflation and deflation was done for analysis of esophageal cross-sectional area, compliance, and hysteresis monthly during six months. At sacrifice, the esophageal collagen content was determined. A small but statistically insignificant increase in compliance was observed during the six-month observation period in both groups. No differences were observed between the groups (P greater than 0.3). No change in hysteresis was observed in either group. The group with esophageal varices had significantly higher collagen content in the distal esophagus when compared to controls (P less than 0.05). No difference was demonstrated in the proximal part. No correlation was demonstrated between the collagen content and esophageal compliance. The study demonstrated that the method allows measurement of luminal cross-sectional area and tissue elasticity. No relationship was found, however, between the collagen content and compliance of the rabbit esophagus.

Animals↗
PubMed1991

Cytomegalovirus-specific cell-mediated immune responses in heart and heart-lung transplant recipients are not predictive for the occurrence of symptomatic CMV disease or tissue rejection.

To study the predictive value of interferon-gamma (IFN-gamma) production in vitro for the occurrence of symptomatic CMV disease, 17 healthy adult volunteers were tested and 37 heart or heart-lung transplant recipients (CTRs) were studied at various time intervals after transplantation (Tx) for cell-mediated immune (CMI) responses to cytomegalovirus (CMV). At all intervals post Tx, in vitro IFN-gamma production in CTRs was significantly lower than in control subjects. The occurrence of CMV infection was associated with a trend toward inhibited CMI responses prior to the diagnosis, in comparison with CMI responses measured more than 4 weeks prior to or after the diagnosis of CMV infection. The occurrence of acute tissue rejection was associated with a trend toward enhanced CMV responses prior to the diagnosis, on the other hand. In the early post Tx period, the administration of antithymocyte globulin (ATG) or OKT3 monoclonal antibody and peak dosages of azathioprine were associated with significantly inhibited in vitro IFN-gamma production. Despite the demonstrated trends in vitro, IFN-gamma production does not appear to be uniformly predictive for the occurrence of symptomatic CMV disease or of acute tissue rejection in CTRs.

Adult↗
PubMed1991

Antibody response to human cytomegalovirus glycoproteins gB and gH after natural infection in humans.

Antibody to the recombinant gB (rgB) and recombinant gH (rgH) glycoproteins of human cytomegalovirus (CMV) was studied in immunocompetent and immunocompromised humans by immunoprecipitating [35S]methionine-labeled CHO cell lines stably expressing rgB and rgH. Antibody to the rgB precursor was present in greater than 60% of immunocompetent individuals. However rgH antibody was detected in less than 10% of these patients. Antibody to both the rgB and rgH was detected during convalescence in three immunocompetent individuals with symptomatic CMV mononucleosis but to a lesser extent in three others who seroconverted to CMV without symptoms. Antibody to rgB and rgH in heart and heart-and-lung transplant recipients was detected in both primary and recurrent CMV infections but not with the same intensity as in immunocompetent individuals. Selected lots of immune serum globulin, administered prophylactically to bone marrow transplant recipients, were frequently deficient in antibody to rgH but not to rgB.

Animals↗